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Cylinders in Series

Anonymous said...


Can a single directional control valve operate 2 cylinders if each cylinder uses a breather valve instead of a return line so that one cylinder would push the other closed?

November 23, 2009 6:25 AM

Reversing a cylinder

bret said...


Where can i find a valve that changes the direction of a cylinder by stopping flow or presure then restoring flow or presure? I need double action on a single action circut at 70 gpm. thanks

Mono Block Valve

hydo said...
Sorry but i forgot how to post a new question and just jumped in this .
iam having a problem with gear pump witch is connected via a monoblock to a pressure guage.
problem is that when i switch the dcv 'on' the guage showes 190 bar ,but for just for one second
then it start to go doun to 100 bar and stay at 100 bar.

as i switch off and then on again
it goes to 150 and then goes down again.
is it relief walve which is releasing pressure and not settlig down again till pressure goes down to 100 bar , if it is pressure should rise again .can a pilot oprated relief solve this .
forgive me for a so basic and not mind frying question.

January 5, 2010 3:51 AM

Snow Auger

Anonymous said...
I have a 36 inch snow auger that needs to be run at 900-950rpms. What size hydraulic pump and motor would i need to run it. I have a 2 cylinder 13hp honda gas motor that i am going to use to power it.

Log Splitter Valve

Anonymous said...
I am building a log splitter with a log lift. I have two single spool log splitter valves with detents. Can I use them both in tandem? If so is there anything besides the hose between them needed to do it?
August 21, 2009 4:04 PM

Impulse Test Flow Rate

Valliappan said...
I wanted to do impulse test on a cylinder in fully retracted condtion. Cylinder size Bore 100mm, Rod 60 mm, stroke 1000mm. The annular volume is 5.026 ltrs. The pressure has to be rised from zero to 410 bar in 60 mill sec and brought back to zero (sinosoidal wave). We have to do impulse at the rate of 8Hz. What will be the pump flow reqd to this impulse test assuming the cylinder is initially filled with oil and the pump is reqd to rise the pressure to 410 bar.
August 19, 2009 1:53 AM

Stopping a Cylinder When Pressure is Lost

NL SONI said...
IT IS REQUIRED TO LOCK A VERTICAL SERVO HDRAULIC LINEAR ACTUATOR HANDLING A DEAD WEIGHT WHENEVER A LOSS OF PRESSURISED OIL SUPPLY TO THE ACUATOR. IT SHOULD INSTANTLY STOP AND GET LOCK AT THE SAME POSITION AT THE TIME OF OIL SUPPLY FAILURE.THE OPERATING PRESSURE IS ABOUT 20 BAR TO 100 BAR.KINDLY SUGGEST THE WORKABLE SOLUTION FOR THIS REQUIREMENTS.
August 18, 2009 9:26 PM

Suction Line Oil Level

I borrowed this topic from the H & P Forum but I have seen some discussion about my posts:

If positive displacement pump is running and stopped , pump is mounted on tank and suction length above oil level is 200 mm and there is no leakage in suction line and suction chamber ,whether the oil will remain full in suction line after pump stoppage . Will it fall down ?

What happens if length is 400 mm, 800 mm, etc.

Piston Seal Leakage - Rod Down

We have a cylinder mounted with the rod pointing down. It has a weight on the end of the rod.
There is a ball valve at each cylinder port.

Assumptions:

1. Piston seals are leaking badly
2. Rod seal does not leak
3. Ball valves, when closed, do not leak

What happens when the cylinder is fully retracted and both ball valves are closed?

Flow Control - Mislabeled???

How does a flow control control flow since all the oil in equals all the oil out?

Vertical Cylinder Question

Single Rod Cylinder - vertically mounted with rod up
10" Bore, 4" Rod, 10" stroke
Cap is vented to atmosphere and Rod end is plugged; assume no leakage.
Cylinder is about 3/4 extended.
What happens when a 500 lb load is applied to the rod?

Change in Load Question

The system consists of a fixed RPM electric motor, fixed displacement pump, system relief, cylinder, directional valve, and reservoir. If the cylinder is extending at a constant speed and the load opposing cylinder travel increases what happens to the speed of the cylinder?

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Regenerative Circuit Question

Are the pressures on the Cap side and Rod side of a cylinder in a regenerative circuit equal?

Pressure Compensation

The flow across any hole is determined by the pressure drop or differential pressure across the hole and the temperature of the fluid. Pressure compensation keeps the pressure drop across the hole relatively constant regardless of the inlet or outlet pressure at the hole.

Understanding the Spring

The spring is an essential part of any hydraulic system. One must understand the deflection vs force on the spring; this is called the spring constant. The greater the spring is deflected from its free state the more force it takes to deflect it further. This is a linear relationship. Cracking pressure is a result of the preload on the spring. Pressure drop vs flow is a result of the spring constant and the square root relationship of pressure drop vs flow during turbulent flow.

Pump Pressure

Question of the day: What 2 things determine pressure at the pump outlet?

Balance of Forces/Cylinder

A cylinder will travel at a constant velocity from 0-100% as long as the forces on both sides of the piston, the load force, and any other forces such as friction are in balance. When the forces are not in balance the piston and rod will accelerate (positively or negatively) until the forces are once again in balance.

Hydraulic Application - Hydrostatic Pump circuit for Double Acting Cylinder